Provence · about 1 km from Cassis
Source du Bestouan
- Max depth33 m
- CertificationFull cave
- Water temperature≈ ~15 °Cestimated, no reports yet
- SpecialSidemount
Diving and fills
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Fills nearby
- Fill stationCassis Calanques PlongéeNitrox and trimix (tech and CCR courses); which gases visitors can have filled, and to what pressure: askRoute ↗
- Fill stationKraken Plongée (La Ciotat)Air, nitrox, oxygen and helium; fills at 230 and 300 barRoute ↗
- Fill stationPlongée Tek MarseilleFills diluent (air, trimix) and O₂ for its own CCR and trimix students; fills for visitors: askRoute ↗
What it looks like
Plongée souterraine - Rivière du Bestouan - Cassis - [Tuto de plongée n°6] (Le Bestouan à Cassis) Plongée Bestouan à Cassis juin 2016 Le Bestouan - Cassis
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Videos and posts
From other divers, via YouTube, Instagram and Facebook. They only load when you click; after that, Google's or Meta's privacy rules apply.
Plongée souterraine - Rivière du Bestouan - Cassis - [Tuto de plongée n°6] (Le Bestouan à Cassis) Plongée Bestouan à Cassis juin 2016 Le Bestouan - Cassis
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Other people's footage, not advice: how someone else dives here says nothing about what suits your team. Dive within your training.
The dive
A submarine karst river on the west side of Cassis harbour; it makes Bestouan beach noticeably cooler. The outflow is strong (>1 m³/s): on the way out the current pushes you.
1 earlier accident or incident has been reported at this cave. Read what happened ↓
Profile and sections
A submarine karst river on the west side of Cassis harbour; it makes Bestouan beach noticeably cooler. The outflow is strong (>1 m³/s): on the way out the current pushes you. Where fresh and salt water mix there is a halocline: a fog layer in which you see nothing. Thick clay deposits cover the floor, and visibility at the entrance is often poor. The water is ~15 °C. There is a fixed line, at least for the first ~150 m. A normal dive takes ~1 hour (without deco).
The Cassis – La Rivière Mystérieuse association carries out measurements and surveys here.
Practical: FFESSM Provence holds discovery days here.
- Depth and profile
- Entrance: ~1 m cross-section conduit at -1 m, ~30 m long, to the top of a shaft down to -15 m · then a gallery 3–6 m wide and 3–4 m high at -20 to -24 m · max -33 m · development 3,750 m, longest sump 3,000 m · air bells at ~700, 1,300, 1,700, 1,825 and 2,025 m · terminal chamber ~3 km upstream (30 m wide, 35 m high)
- Configuration
- Classically dived with a twin set (at least 2× 15 l, FFESSM). Sidemount passes the tight, shallow entrance more easily. CCR is possible, but the entrance at -1 m is tight and exposed to swell. Explorers use scooters in the long gallery.
- DPV: DPV possible (estimate)
- Long gallery (3 km) where explorers use scooters (navigation console on the scooter since 2017). The tight entrance (~30 m, 1 m cross-section) makes taking one in awkward; little gain for a normal dive.
Who can dive where
- At least Full cave
- Configurations: Backmount / twinset / Sidemount / CCR / Small cylinders / no-mount (speleo sumps)
- Goes down to 33 m (trimix or deco may be needed)
- Experienced divers only
This is how the planner decides who in your team may dive this cave. Rules your own trip adds (organizer, a mail, the AI) show with your trip.
How to get there
Shore dive. Park in the paid Bestouan car park and walk towards Cassis. Enter from Bestouan beach (left side, by the harbour) or from the rocks past the lighthouse (2 m jump, ladder to get out). Then ~100–200 m surface swim to the entrance at -1 m (bearing 40° from the base of the orange lighthouse). You cross a bathing zone and the harbour entrance: heavy boat traffic, and according to a dive-site database diving there is formally not allowed — check the rules with the Cassis harbour office.
Around Source du Bestouan
Fills3 fill stations · nearest 1 km
Cassis Calanques Plongée
Port de Cassis, 13260 Cassis
Nitrox and trimix (tech and CCR courses); which gases visitors can have filled, and to what pressure: ask
Open all year; ask for hours
Dive centre with a boat at Cassis harbour (formerly Centre Cassidain de Plongée), inside the Parc national des Calanques; tech diving (trimix, rebreather) and CCR courses. Close to the Bestouan and Port-Miou. CCR support and sofnolime: ask.
Kraken Plongée (La Ciotat)
Base nautique, Nouveau Port de Plaisance, Av. du Président Wilson, 13600 La Ciotat
Air, nitrox, oxygen and helium; fills at 230 and 300 bar
Ask
CCR support: oxygen, booster and sorb
The premises on rue Piroddi are temporarily closed; come to the base nautique in the Nouveau Port.
Dive centre with a rEvo rebreather workshop and tech courses; two RIBs (7.5 and 6 m, 24 divers in total). CCR support: sorb (Sofnolime 797) in 20 kg drums or loose. Details confirmed by Kraken Plongée, Oct 2026.
Plongée Tek Marseille
Port de la Pointe Rouge, 13008 Marseille
Fills diluent (air, trimix) and O₂ for its own CCR and trimix students; fills for visitors: ask
Ask
Tech centre in Pointe Rouge harbour, the departure point for the Calanques and the Riou archipelago. CCR courses on rEvo, JJ-CCR, Shark, Triton and AP Inspiration; CCR trimix to -70 m. CCR and scooter rental: ask. Also +33 6 72 05 50 16.
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News
All (1)
Accidents and incidents
What happened at this cave before, with the sources. No names are given; read it as a lesson for your own planning.
- Fatal accident in January 2020: one diver of a group of four did not return; the diver was found ~300–400 m from the entrance.
Access and rules change: check what applies locally right before your trip. Source: GDELT Project and the news feeds of diving magazines. Search for more news ↗ Searched automatically, last on 13 Nov 2026.
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